Many liquid and semi-liquid products are packaged into large containers for storage and distribution to repackagers, commercial uses and other users of large quantities of the product. Many of these products, particularly food products, deteriorate rapidly when exposed to oxygen. Additionally, food products must be protected against possible contamination from bacteria. Therefore, these products are often placed in large (e.g. one to six gallon) containers made of plastic or similar material and having one spout through which the container is filled and from which the product is dispensed from the container. These plastic containers are advantageous in that as the product is dispensed from the container, the container collapses around the remaining material so that no air enters the container. With container of a fixed shape or internal volume, air must enter the container to fill the volume left in the container as the product is dispensed. This air contains oxygen and frequently carries harmful bacteria. These containers typically have a rigid or semirigid plastic spout through which the product passes to enter or leave the container. In addition, care must be taken in packaging food products into the containers that no bacteria could enter the container that would create a potential health risk to the consumer of the food product.
To ensure the sterility, it is disclosed in U.S. Pat. No. 4,458,734 issued to Scholle et al. that the container is filled inside a filling chamber that maintains a sterile atmosphere around the spout of the container. The filling chamber is sterilized and is filled with a sterile gas, with the gas maintained in the chamber at a positive pressure with respect to the outside environment. The positive pressure of the gas ensures that no air from outside the chamber enters the chamber, as the flow through any opening in the chamber walls is from the higher pressure interior to the lower pressure exterior. A filling head is provided inside the chamber for filling the container with the fluid. An opening is then provided in the bottom of this chamber that is large enough to receive the spout of one of the plastic container food containers. Once the spout is placed in the opening, it is brought into contact with the filling head and the fluid is dispensed into the container.
One of the main deficiencies of the Scholle's invention is the lack of ability to clean the spout of the container. The spout of the container contributes to the contamination in two ways. First, after filling the fluid into the container, some residual fluid is stuck onto the inner wall of the spout opening of the container which then causes contamination to the fluid contained in the container. The other source of contamination is that bacteria stuck onto the inner surface of the spout is brought into the filling chamber when the spout of the container is lifted into the filling chamber. Therefore, in order to prolong the shelf life of the packaged products, a new method or apparatus is needed to reduce the two abovementioned contaminations.
In U.S. Pat. No. 4,893,659 issued to Loeliger, it is disclosed a filling head apparatus having valves at the tip of the head for regulating flow of a sterilizing medium and regulating flow of a fluid to be filled in a container to a filling head space. The Loeliger disclosure is directed to the resterilization of the spout opening of the container after filling and discloses a filling head combined with a sterilizing medium dispersion valve at the tip of the head to sterilize the spout of the container. However, the Loeliger's design specifically requires a steam outlet passage connected to the side of the tip of the filling head for the escape of the steam introduced. Therefore, for the Loeliger's system, an extra pipe is needed to connect to the tip of the filling head for the draining of the escaping steam. Because the sterile chamber is very small and the Loeliger disclosure requires this extra steam outlet connected to the tip of the filling head, the Loeliger's disclosure is not practical to be implemented in a sterile chamber. Therefore, a new design on the filling head is needed for the sterilization of the spout of the container.
Another aspect of the present invention is directed to an apparatus and a method of increasing the overall throughput of the filling apparatus by eliminating or minimizing the "water hammer" effect caused by the opening and closing of a fluid regulating valve. The water hammer effect usually occurs when the fluid flowing through the filling head into the container is quickly shut off. This hydraulic shock reduces the servicing life of the filling system by applying strong loads to the piping and filling head as well as causing noise. The effect is conventionally minimized by slowly shutting off the fluid flow to the filling head, however, with the expense of slowing down the filling process. Therefore, the entire system throughout deteriorates proportional to the slowing of the shut off valve. The present invention discloses a new and improved filling head to allow quick closure of the fluid flowing into the container while able to minimize the water hammer effect on the filling system.